Field of Technology
This disclosure relates to a fingerprint sensor integrated type touch screen panel, in particular a fingerprint sensor integrated type touch screen panel capable of perceiving a fingerprint.
Discussing of the Related Art
In recent years, computer based systems applied to various utilities, such as tablet personal computers (PCs), smart phones, personal digital assistants (PDAs), automated teller machines (ATMs), and information systems have been developed according to growth of computer techniques. In general, the computer based systems store various data including secret information such as business information and business secret as well as personal information related to private affairs. Accordingly, it is required to strengthen security to protect the secret information.
To this end, fingerprint sensors have been developed to strengthen security by performing system registration or certification using fingerprints of a human being.
The fingerprint sensor is a sensor capable of sensing fingerprints of a human being. The fingerprint sensor is classified into an optical fingerprint sensor and a capacitive fingerprint sensor.
The optical fingerprint sensor utilizes a principle in which a light source such as a light emitting diode (LED) emits light, and senses the light reflected from ridges and valleys of a fingerprint through CMOS image sensors. There are some problems such as an increase in size due to the use of LEDs and rise in product cost due to the use of expensive light source.
The capacitive fingerprint sensor utilizes difference of electric charges charged between ridges and valley of the finger contacted thereto.
U.S. Patent Publication No. 2013/0307818 published on Nov. 21, 2013, and entitled “Capacitive Sensor Package” is known as the related art capacitive fingerprint sensor.
The published capacitive fingerprint sensor is constructed as an assembly form engaged with a particular push button. The capacitive fingerprint sensor includes a silicon wafer to which a circuit for measuring an electrostatic capacitance between the fingerprint (ridges and valleys) and a capacitive plate is printed.
In general, it is necessary for the capacitive fingerprint sensor to have a high resolution sensor array and an IC for a fingerprint recognition because the finger's ridges and valleys have a very minute size of about 300 μm to about 500 μm. To this end, the capacitive fingerprint sensor utilizes the silicon wafer for integrating the IC with the sensor array.
However, in case of integrating the IC with the high resolution sensor array using the silicon wafer as described in the US Patent Publication No. 2013/0307818, it is necessary for the capacitive fingerprint sensor to have an assembly construction for coupling the fingerprint sensor with a push button. Accordingly, there are some problems such as a complicated construction and an increase in bezel area (non-display area) in the optical fingerprint sensor due to the assembly construction. Also, there are other problems including the issue that thickness is increased and an area for sensing the fingerprint depends on the size of the push button (e.g., a home key of a smart phone) because the push button overlaps the fingerprint sensor.
To resolve the problems mentioned above, technologies have been developed for utilizing an area of a touch sensor screen as an area of a fingerprint sensor for identifying a fingerprint. As the techniques, there are known U.S. Pat. No. 8,564,314 issued on Oct. 22, 2013 and entitled “Capacitive Touch Sensor for Identifying a Fingerprint”, and Korea Patent No. 10-1432988 issued on Aug. 18, 2014 and entitled “Fingerprint Integrated type Capacitive Touch Screen”.
FIG. 1 is FIG. 5 shown in U.S. Pat. No. 8,564,314, and is a plan view schematically illustrating an arrangement of driving electrodes and sensing electrodes of the capacitive sensing panel, and the FIG. 2 is FIG. 2 shown in Korean Patent No. 10-1432988, and is a plan view illustrating the fingerprint sensor integrated type capacitive touch screen.
Referring to FIG. 1, the capacitive touch sensor includes a touch position sensor 403 and a fingerprint sensor 405. The touch position sensor 403 has touch driving electrodes 401(x) and touch sensing electrodes 401(y). However, in the capacitive touch sensor 400, the fingerprint sensor 405 is disposed only in a portion of the display area. Therefore, the area where the fingerprint sensor 405 is disposed cannot be acted as a touch area. Also, a touch performance may be degraded at a peripheral region of the fingerprint sensor 405.
Referring to FIG. 2, the fingerprint sensor integrated type capacitive touch screen includes a touch panel 110, electrode connecting lines 120 and a touch controller 130. The touch panel 110 includes fine channels 113 formed by combinations of the first channel electrodes 111 and the second channel electrodes 112. The fine channels 113 have first fine channels and second fine channels. The first fine channels are disposed in the display area excluding the region of the fingerprint sensor 405. The second fine channels are disposed in the region of the fingerprint sensor 405. The first fine channels are grouped in plural and functioned as touch channels 115. The second fine channels are functioned as fingerprint recognition channels 116. However, in the fingerprint sensor integrated type capacitive touch screen, mutual capacitances between the first channel electrodes 111 and the second channel electrodes 112 are significantly increased because of the second fine channels functioned as the touch channels 115. According to the increase of the mutual capacitance, touch sensibilities of the fingerprint sensor integrated type capacitive touch screen are degraded, thereby making touch recognition impossible when a touch event is performed.